Cooling device for electromagnetic induction type cookin heater

ABSTRACT

It is an object of the present invention to provide a light and compact cooling device which is possible to use an alternating magnetic field generated in an electromagnetic induction type cooking heater which is usually used as a heater, as an energy source of the cooling device. The cooling device to be mounted on a plate of an electromagnetic induction type cooking heater including a coil by which a magnetic field is generated, the cooling device including a plurality of Peltier devices comprised of two kinds of metals or semiconductors, Peltier devices comprised of the first kind of metal or semiconductor and Peltier devices comprised of the second kind of metal or semiconductor being alternately arranged, the Peltier devices being electrically connected in series to one another through electrode plates ( 3, 4 ) to define a Peltier module A so that heat-absorption sides thereof are on the same side and heat-production sides thereof are on the other side, an electrical conductor ( 8 ) and a rectifying diode ( 7 ) being electrically connected to the electrode plates ( 3, 4 ) situated at the opposite ends of the Peltier module A.

FIELD OF THE INVENTION

The invention relates to technology for using Peltier devices as acooler by virtue of an induced current generated by a high-frequencyinduction magnetic field, which is a principle for generating heat in anelectromagnetic induction type cooking heater (IH cooking heater).

BACKGROUND ART

Recently, an electromagnetic induction type cooking heaters are broadlyused as a highly safe cooking devices, because they do not use a flame,and do not possibly cause monoxide gas poisoning compared with cookingdevices using gas.

In an electromagnetic induction type cooking heater, a coil which willgenerate a magnetic field is positioned beneath a plate composed of anelectrically insulating material. Causing high-frequency waves (having awavelength in a GHz order) to flow through the coil, there analternate-current magnetic field is generated, and thus, eddy currentsare induced in a metal (for instance, iron) pan put on the plate. As aresult, there Joule's heat is generated in accordance with resistance ofthe metal of which the pan is composed, and hence, the pan is heated.The electromagnetic induction type cooking heater operates on the basisthat a pan itself is heated by virtue of induced eddy currents.

The patent reference 1 suggests a cooking device which can heat and coola food. The cooking device is designed to have an upper portionprojecting from an upper surface of a body to place food thereon, and toinclude a temperature controller to carry out heat exchange between thefood and the cooking device to thereby heat and cool the food. Thecooking device heats and cools a food by causing a direct current toflow into Peltier devices. However, Peltier devices merely have acapacity to heat food at such a temperature that the food is kept atabout 100 degrees centigrade. Accordingly, Peltier devices are notsuitable for frying foods because it is necessary to heat a food at ahigh temperature for frying the food, and thus, it is necessary toprepare an electromagnetic induction type cooking heater as anotherdevice for frying foods.

The patent reference 2 suggests a heating/cooling device including aheater having a heating plate to be induction-heated by a heating coil,and a Peltier module chamber having a Peltier module comprised ofPeltier devices for cooling a food.

The patent reference 3 suggests a food warmer which covers a foodtherewith to thereby warm the food. The food warmer includes anelectronic cooler comprised of Peltier devices, and positioned at asummit of a cover having an outer surface composed of a highheat-insulating material and an inner surface composed of a highheat-conductive material, for cooling what is included in the cover.

Patent Reference 1: Japanese Patent Application Publication 2004-335447Patent Reference 2: Japanese Patent Application Publication 2003-148850Patent Reference 3: Japanese Patent Application Publication 11-276358DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Recently, cooking devices to be used in households are turning to beelectric appliances together with life style being varied, and tastesfor household cooking are changing remarkably. With propagation of anelectromagnetic induction type cooking heater, various cooking processesare carried out. In some cooking processes, the food is cooled afterfirst heating. Thus, there is a need for cooking devices which can notonly heat a food, but also cool a food.

An existing electromagnetic induction type cooking heater is usuallyfixed in a kitchen, or used on a plate. Thus, if a food needs to becooled, it is necessary to prepare ice or a cold insulator having beencooled in advance in a refrigerator, resulting in time consumption inpreparation and clean up. A presently available cooking device is ableto heat a food together with a gas cooking device, an electromagneticinduction type cooking heater and so on, but is not suitable for coolinga food.

As cooking tools which are able to cool a food, we can find some assuggested in the above-mentioned patent references 1 to 3, and as acooking tool which is able to both heat and cool a food, we can find oneas suggested in the patent reference 1. However, as mentioned earlier,Peltier devices for heating and cooling a food in the patent reference 1cannot present a high temperature for heating a food for cooking.Accordingly, it is additionally necessary to prepare an electromagneticinduction type device, and Peltier devices and the electromagneticinduction type device are alternately and inconveniently operateddepending upon whether a food is to be heated or cooled.

Furthermore, since every household already has some cooking devices, ifa function of cooling a food were necessary, every household would haveto reform an existing electromagnetic induction type cooking heater, ornewly purchase the cooking device as suggested in the patent reference1.

However, presently available electromagnetic induction type cookingheaters are all expensive, and an electromagnetic induction type cookingheater having a function of cooling foods, such as the one suggested inpatent reference 1, is expected to be even more expensive. Thus, it isnot practical to exchange a presently used device into theabove-mentioned device for carrying out a certain cooking process whichis usually carried out at a low frequency, except newly purchasing theabove-mentioned device.

Since the cooling devices as suggested in the patent references 2 and 3cover a food therewith, it is not possible to cool a food while cookingthe same.

Furthermore, since the cooling devices suggested in the patentreferences 1 to 3 are designed to necessarily have a commercialelectric-power source as an energy source for activating Peltier devicescomprising the cooling devices, and to control the temperature by meansof a temperature controller equipped therein, the cooling devices areunavoidably complex in structure because they have to include a circuitfor controlling the temperature, resulting in such problems as, they areexpensive, they cannot be compact, they are heavy, they are difficult tocarry, and they unavoidably have obstructive codes. Thus, the coolingdevices are not broadly used.

It is an object of the present invention to provide a light and compactcooling device which is capable of cooling a food while cooking the samewithout using a commercial electric-power source merely by putting thecooling device on a plate of a turned-on electromagnetic induction typecooking heater, and an electromagnetic induction type cooking heaterwhich can be used not only as a heater, but also as a cooler withoutnewly purchasing the same in place of an existing electromagneticinduction type cooking heater used as a heater in each household.

Solution to the Problems

In order to achieve the above-mentioned object, the present inventionprovides, in a first aspect, a cooling device to be mounted on a plateof an electromagnetic induction type cooking heater including a coil bywhich a magnetic field is generated, wherein an energy source of thecooling device is presented from an alternating magnetic field generatedin the electromagnetic induction type cooking heater.

In the first aspect, an alternating magnetic field generated by themagnetic field generating coil of the electromagnetic induction typecooking heater is used as an energy source for activating the coolingdevice. Thus, it is no longer necessary to use an external power sourcefor activating the cooling device, and it is no longer necessary for thecooling device to include a wire to be electrically connected to acommercial electric-power source.

In a second aspect of the present invention, the cooling device isdesigned to include Peltier devices comprised of two kinds of metals orsemiconductors. The second aspect makes it possible to achieve a coolingdevice eliminating the need for a power source.

In a third aspect of the present invention, the cooling device furtherincludes an electrical conductor and a rectifying diode both defining aclosed-loop circuit together with the Peltier devices to provide adirect current as an energy source to the Peltier devices.

In the third aspect, an alternating magnetic field generated by themagnetic field generating coil of the electromagnetic induction typecooking heater is received in the closed-loop circuit, and then, isconverted into a direct current through the rectifying diode. The directcurrent is introduced into Peltier devices, resulting in theheat-absorption sides of Peltier devices being cooled. The contents of apan or a container having a flat bottom that is placed on theheat-absorption sides of Peltier devices, what is contained in the panor container is cooled.

The present invention provides, in a fourth aspect, a cooling device tobe mounted on a plate of an electromagnetic induction type cookingheater including a coil by which a magnetic field is generated, thecooling device including a plurality of Peltier devices comprised of twokinds of metals or semiconductors, Peltier devices comprised of thefirst kind of metal or semiconductor and Peltier devices comprised ofthe second kind of metal or semiconductor being alternately arranged,the Peltier devices being electrically connected in series to oneanother through electrode plates to define a Peltier module such thatheat-absorption sides thereof are on the same side and heat-productionsides thereof are on the other side, an electrical conductor and arectifying diode being electrically connected to the electrode platessituated at the opposite ends of the Peltier module.

In the fourth aspect, the Peltier module is defined by arranging aplurality of Peltier devices in such a way as mentioned above, ensuringa broad area for cooling a food. Furthermore, since a plurality ofPeltier devices is arranged to define a part of a loop, it is possibleto enhance an efficiency for cooling a food.

The cooling device in accordance with a fifth aspect of the presentinvention is designed to further include, in comparison with the fourthaspect, a coil interlinking with an alternating magnetic field generatedin the coil by which a magnetic field is generated is electricallyconnected the opposite ends of the Peltier module through the electricalconductor and the rectifying diode.

Thus, a magnetic field generated by the magnetic-field generating coilis amplified in accordance with a number of turns of the coil, andaccordingly, since a current running through the Peltier module can bemade higher in an amount, it is possible to enhance performance ofcooling a food.

In a sixth aspect of the present invention, the cooling device furtherincludes a cooler for cooling the Peltier module at its heat-productionside.

This ensures that it is possible to prevent the temperature at theheat-absorption sides from being lowered at a degree at which atemperature at the heat-production sides is lowered by cooling, andfurther prevent the temperature at the heat-absorption sides from beingraised due to raising of the temperature at the heat-production sides,to thereby prevent the declining efficiency of cooling a food. Thus, ahighly practicable cooling device to be used for electromagneticinduction type cooking heater can be archived.

ADVANTAGES PROVIDED BY THE INVENTION

The present invention provides a cooling device to be mounted on a plateof an electromagnetic induction type cooking heater including a coil bywhich a magnetic field is generated, wherein an energy source of thecooling device is presented from an alternating magnetic field generatedin the electromagnetic induction type cooking heater. Thus, it ispossible to use an alternating magnetic field generated in anelectromagnetic induction type cooking heater which is usually used as aheater, as an energy source of the cooling device. Hence, it is possibleto use the electromagnetic induction type cooking heater not only as aheater, but also as a power source for a cooling device. Furthermore,since a temperature control in the cooling device can be accomplished byan intensity control of an alternating magnetic field generated in theelectromagnetic induction type cooking heater, it is not necessary forthe cooling device to include a complex control circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the principle of a Peltier module making use of Peltiereffect.

FIG. 2 shows the principle of an electromagnetic induction type cookingheater.

FIG. 3A is a cross-sectional view of the Peltier module in accordancewith the embodiment of the present invention.

FIG. 3B is a plan view of the Peltier module in accordance with theembodiment of the present invention.

FIG. 4 shows the principle of the operation of the first embodiment.

FIG. 5 shows the principle of the operation of the second embodiment.

FIG. 6 is a circuit diagram illustrating an example for feeding electricpower to the Peltier module operating in accordance with the principleof the second embodiment.

FIG. 7 is a circuit diagram illustrating another example for feedingelectric power to the Peltier module operating in accordance with theprinciple of the second embodiment.

FIG. 8 is a cross-sectional view of a specific example of cooling devicein accordance with the present invention, to be used for anelectromagnetic induction type cooking heater.

INDICATION BY REFERENCE NUMERALS

-   1 P-type semiconductor-   2 N-type semiconductor-   3, 4 Electrode plate-   5, 6 Ceramic plate-   7 Diode-   8 Electrical conductor-   11 Top plate-   12 Magnetic field generating coil-   13 Pan

BEST EMBODIMENT FOR REDUCING THE INVENTION TO PRACTICE

Embodiments in accordance with the present invention will be explainedhereinbelow with reference to drawings.

First, the Peltier effect is explained hereinbelow with reference toFIG. 1.

The Peltier effect is that if a current flow through a junction throughwhich two metals or semiconductors, are joined with each other, heattransfers from one of the two metals or semiconductors to the othermetal or semiconductor. A Peltier module is constructed as follows onthe basis of this principle. As illustrated in FIG. 1, P-typesemiconductors 1 and N-type semiconductors 2 are alternately arranged ona plane, and the semiconductors 1 and 2 are electrically connected inseries through metal electrode plates 3 and 4 to thereby define aPeltier module. By causing a current to flow through the Peltier module,one of the electrode plates, for instance, the electrode plate 4 acts asa heat-absorption side, specifically, is cooled. The other electrodeplate, that is, the electrode plate 3 acts as a heat-production side,specifically, is heated.

FIG. 2 shows a principle of an electromagnetic induction type cookingheater. A magnetic field generating coil 12 is positioned beneath a topplate 11 composed of heat-resistance glass. By causing a high-frequencycurrent to run through the magnetic field generating coil 12, analternating magnetic field is generated in the magnetic field generatingcoil 12. Putting an iron pan 13 on the top plate 11, eddy currents “ie”are induced at a bottom of the iron pan 13. Since the eddy currents runthrough a resistance of iron of which the pan 13 is composed, thereJoule's heat is generated, resulting in the pan 13 being heated at thebottom thereof, and hence, the food contained in the pan 13 is heated.

In the present invention, a current generated in a closed-loop circuitdefined on the top plate 11 due to an alternating magnetic fieldgenerated in the magnetic field generating coil 12 of theelectromagnetic induction type cooking heater interlinks with theclosed-loop circuit is used as a power source to thereby operate thePeltier module as a cooling device.

Specifically, as illustrated in FIGS. 3A and 3B, P-type semiconductors 1and N-type semiconductors 2 are alternately arranged on a plane, and thesemiconductors 1 and 2 are electrically connected in series throughmetal electrode plates 3 and 4 to thereby define an arrangement like apicture drawn with a single stroke of a brush. The semiconductors 1 and2 may be arranged in a spiral. Ceramic plates 5 and 6 are adhered to theelectrode plates 3 and 4 to thereby define a Peltier module. A. Theelectrode plates 3 disposed at the opposite ends are electricallyconnected to each other by electrical conductor 8 through a diode 7, tothereby define a closed-loop circuit.

In the above-mentioned structure, an alternating magnetic fieldgenerated in the magnetic field generating coil 12 of theelectromagnetic induction type cooking heater is introduced into theclosed-loop circuit defined by the Peltier module “A” and the electricalconductor 8, and is rectified by the diode 7. Thus, a current runningtoward a single direction, that is, a direct current runs through thePeltier module “A”, and resultingly, heat accumulated in the ceramicplate 6 is absorbed. As a result, putting a pan (preferably, composed ofan electrical insulator such as glass) on the ceramic plate 6, what iscontained in the pan is cooled. Since the other ceramic plate, that is,the ceramic plate 5 acts as a heat-production side, it is possible toenhance the cooling efficiency by causing the ceramic plate 5 to makecontact with a cooling medium circulated in a radiator (mentioned later)to thereby cool the ceramic plate 5.

Then, the principle of the operation of the first embodiment inaccordance with the present invention is explained hereinbelow withreference to FIG. 4. Putting the Peltier module “A” on the top plate 11of an electromagnetic induction type cooking heater, there is generatedan alternating magnetic field perpendicularly to the magnetic fieldgenerating coil 12 by virtue of a high-frequency current running throughthe magnetic field generating coil 12 (see FIG. 2) disposed beneath thetop plate 11. The alternating magnetic field induces a current into aclosed-loop circuit defined by the Peltier module “A”, the diode 7 andthe electrical conductor 8. The current is rectified by the diode 7, andthus, the current runs through the P-type semiconductors 1 and theN-type semiconductors 2 defining Peltier devices in the Peltier module“A”, in a single direction, and resultingly, the Peltier module iscooled at a surface thereof. Putting a pan or container on the Peltiermodule “A”, a food contained in the pan or container is rapidly cooled.

Then, the principle of the operation of the second embodiment inaccordance with the present invention is explained hereinbelow withreference with FIG. 5. In the second embodiment, a coil 9 is disposedunder the Peltier module “A”. The coil 9 and the Peltier module “A” areelectrically connected to each other through an electrical conductor 8and a diode 7. Whereas the closed-loop circuit disposed outside of thePeltier module “A” has a single turn, the coil 9 in the secondembodiment is designed to have a plurality of turns, ensuring that amagnetic field generated in the magnetic field generating coil 12 (seeFIG. 2) can have a great number of interlinkages, and hence, an inducedelectromotive force can be amplified. This is based on that as iftransformers connected to each other through an alternating magneticfield exist across the magnetic field generating coil 12 and the coil 9.Thus, the Peltier module “A” provides a high cooling efficiency, andhigh practicability.

If the single rectifying diode 7 was arranged between the Peltier module“A” and the coil 9, a current running through the Peltier module “A”would have a rectified half-wave waveform, as illustrated in FIG. 6.Accordingly, since an average current is a half of a full wave resultingin low efficiency. Thus, as illustrated in FIG. 7, if a diode bridge A'were used in place of the single diode 7, a current having a rectifiedfull-wave waveform runs through the Peltier module “A”, and accordingly,it would be possible to allow a current to run through the Peltiermodule in an amount twice greater than an amount of a current runningthrough the Peltier module to which the single diode 7 is electricallyconnected. Thus, there can be obtained enhanced cooling performance.

In the explanation having been made above, the electrode plate 4 of thePeltier module “A” is cooled. In a Peltier device, one side is cooledand the other side is heated due to heat transfer. Accordingly, theelectrode plate 3 situated oppositely to the electrode plate 4 isheated. Thus, heat produced at the electrode plate 3 may transfer to thecooled electrode plate 4, and resultingly, the electrode plate 4 may notbe cooled beyond a certain temperature. To avoid this, as illustrated inFIG. 8, a radiator may be connected to the Peltier module.

In FIG. 8, a radiating plate 20 composed of a non-magnetic material suchas aluminum is attached to a lower surface of the Peltier module “A”,and the radiating plate 20 is fixed on an upper surface of a case 21composed of a non-metal material such as plastic. A coil 9 having aplurality of turns and a container 24 containing therein a coolant 23such as water are arranged on an inner bottom of the case 21 such thatthey are situated in the vicinity of the top plate 11 of theelectromagnetic induction type cooking heater. A radiator 25 is disposedoutside of the case 21. The radiator 25 radiates heats contained in thecoolant 23, through a circulation pipe 26. A cooling fan (notillustrated) of the radiator 25 may be driven by introducing ahigh-frequency current induced in the coil 9, thereinto through a wire27.

By arranging the radiator 25 and the circulation pipe 26 in the case 21,it is possible to reduce the space in which they are to be arranged, inwhich case, a user is relieved from the work of arranging the radiator25 and the circulation pipe 26 around the case 21 each time the coolingdevice is used.

One or more commercially available Peltier module(s) “A” may be used.For instance, if twelve Peltier modules were used, each having aspecification of 12V, 6 Amax, and 57 W of maximum heat absorption, totalpower consumption would be 864 W, which can be provided by ahigh-frequency magnetic field generated in an electromagnetic inductiontype cooking heater having output power in the range of 600 to 800 W (ageneral electromagnetic induction type cooking heater has output powerof 1000 W or smaller).

The maximum temperature among temperatures at which the Peltier module“A” can be used is 150 degrees centigrade which is below the temperatureat which solder is melted. Accordingly, if water cooling were selected,a temperature of the Peltier module would not be safely over 100 degreescentigrade. If the heat-production side were at 50 degrees centigrade,the heat-absorption side would be calculated to be at −22 degreescentigrade, ensuring sufficient cooling performance.

As mentioned above, by cooling the heat-production sides of the Peltierdevices, it would be possible to lower a temperature of theheat-absorption sides.

In the above-mentioned embodiments, the Peltier module is put on a plateof the electromagnetic induction type cooking heater, and what iscontained in a pan or a container put on the Peltier module is cooled.Variations may be made to the embodiments as follows.

1. By changing a polarity of the diode, an upper side of the Peltiermodule may be used as a heat-production side. In an electromagneticinduction type cooking heater, if a pan to be placed thereon is composedof a metal having a certain electrical resistance, such as iron, heatwould be produced based on Joule's heat caused by eddy currents. Thismeans that a pan or a container composed of an electrical insulatingmaterial such as glass would not produce heat even if mounted on anelectromagnetic induction type cooking heater. By using the uppersurface of the Peltier module as a heat-production surface, it ispossible to heat a pan mounted thereon, even if the pan is composed ofglass. This indicates that though a glass pan could not be used togetherwith an electromagnetic induction type cooking heater, the presentinvention makes it possible to use a glass pan together with anelectromagnetic induction type cooking heater. Furthermore, anelectromagnetic induction type cooking heater is used for heating afood, and is not suitable for keeping a food warm. Thus, even if thetemperature to be achieved in an electromagnetic induction type cookingheater were set to be low, the cooking heater would provide atemperature achieved by “a low flame”, resulting in the food containedin a pan mounted on an electromagnetic induction type cooking heater fora long time, might be scorched. In contrast, in accordance with thepresent invention, by using an upper surface of the Peltier module as aheat-production surface, it is possible to keep food warm at a lowtemperature, ensuring that the food can be heated for a long time tosuch a degree as to prevent the food from becoming cool.

2. The Peltier module in accordance with the above-mentioned embodimentsmay be formed integral with the bottom of a pan. Thus a cooling pan tobe used only for an electronmagnetic induction type cooking heater isachieved.

3. The electronmagnetic induction type cooking heater may be used as acooling device in a food supplier (for instance, aJapanese-“okonomiyaki” (grill) shop, an inn or a restaurant) in which anelectronmagnetic induction type cooking heater is used as a heat sourcefor heating a food on a table.

For instance, when cooled sweets such as icecream, sherbet or puddingare served after dinner, the electronmagnetic induction type cookingheater may be used to prevent them from melting or prevent thetemperature from rising.

Furthermore, when “sashimi” (raw fish) is first served at a party, thecooling device in accordance with the present invention may be used tokeep them fresh, and after eating “sashimi”, the electronmagneticinduction type cooking heater may be used to grill a food by means of aheating function thereof.

In a restaurant such as a rotary-type “sushi” restaurant, amagnetic-force generating coil may be arranged beneath a conveyer, and adish or a tray into which the Peltier module is embedded in a bottomthereof may be transferred by putting them on the conveyer, in whichcase, it is possible to cool “sushi” or a food to thereby keep themfresh while they are being transferred. A food which is not to be cooledmay be put on a dish in which the Peltier module is not embedded.

INDUSTRIAL APPLICABILITY

The present invention is suitable to kitchen devices to be used inhouseholds or in business by using a Peltier device or Peltier devicesas a cooling device, making use of an induced current caused byhigh-frequency induced magnetic field, which is the principle ofproducing heat in the electromagnetic induction type cooking heater.

1. (canceled)
 2. (canceled)
 3. (canceled)
 4. A cooling device to bemounted on a plate of an electromagnetic induction type cooking heaterincluding a coil by which a magnetic force is generated, said coolingdevice including a plurality of Peltier devices comprised of two kindsof metals or semiconductors, Peltier devices comprised of the first kindof metal or semiconductor and Peltier devices comprised of the secondkind of metal or semiconductor being alternately arranged, said Peltierdevices being electrically connected in series to one another throughelectrode plates to define a Peltier module so that heat-absorptionsides thereof are on the same side and heat-production sides thereof areon the other side, an electrical conductor and a rectifying diode beingelectrically connected to the electrode plates situated at the oppositeends of said Peltier module.
 5. The cooling device as set forth in claim4, further comprising a coil interlinking with an alternating magneticfield generated in said coil by which a magnetic force is generated iselectrically connected said opposite ends of said Peltier module throughsaid electrical conductor and said rectifying diode.
 6. The coolingdevice as set forth in claim 4, further comprising a cooler for coolingsaid Peltier module at its heat-production side.
 7. The cooling deviceas set forth in claim 6, wherein said cooler is comprised of aheat-radiating plate attached to a heat-production side of said Peltiermodule, a case composed of a non-metal material, said heat-radiatingplate being attached to an upper surface of said case, a coil arrangedon a bottom of said case in said case, a container containing therein acoolant and arranged in said case, and a radiator circulating saidcolorant for cooling the same.
 8. The cooling device as set forth inclaim 5, further comprising a cooler for cooling said Peltier module atits heat-production side.